Separation of pyrolusite from calcite by anionic flotation method

In the previous works, the floatability of pyrolusite has been studied using different collectors but the capability of its separation from gangue minerals has not been considered significantly. In this research the flotation behavior of pyrolusite and calcite and their separation from each other using oleic acid as an anionic collector were investigated. The results showed that the pyrolusite flotation recovery contains two peaks at pHs 5 and 9 occurred due to oleate ions physisorption and chemisorptions mechanisms, respectively. Using 10-4 M oleic acid, the maximum flotation recovery of pyrolusite was obtained 30.8% at pH=9. At this condition, flotation recovery of calcite was 68%. It was found that copper sulfate (CuSO4.5H2O) acts as pyrolusite activator and calcite depressant agent in a dosage range of 250 to 1250 g/t. It depresses both minerals at high dosages. The best results were obtained using 1000 g/t copper sulfate in the presence of 10-4 M oleic acid at pH=8. At these condition the flotation recovery of pyrolusite and calcite are 83.6% and 38%, respectively. Copper sulfate increases the pyrolusite surface zeta potential and decreases the electrostatic repulsion forces; and results in the increase in oleate adsorption and flotation recovery. In the ore sample flotation tests, using copper sulfate the MnO grade of the concentrate was increased from 19.1 to 22.7% while the recovery was improved from 40.5 to 66.8%.